“I know they’re upset. I would be too if it were my mother,” the Oscar-winning actress said of Princess Grace’s children, according to Britain’s Daily Mail. “It’s a child’s job to protect their parent. In that regard, I get it. I get why the children are upset.”

“I can’t say much other than that I have great respect and regard for their mother,” she continued.

Grace of Monaco opens the Cannes Film Festival on Wednesday night, and the film has been nothing short of controversial since production began.

Last week, Prince Albert II of Monaco and his sisters Princesses Caroline and Stephanie took the rare precedent of formally denouncing the film about their mother as a “farce,” based on “erroneous and dubious historical references.” It was the second time the children of Grace Kelly attacked the film.

Defending the film, which liberally adapts real events in Monaco’s history into fiction, Kidman told the British paper’s columnist Baz Bamigboye, “It’s not meant to be a biopic. I certainly did my best to honor everything that was real and truthful in it.”

“This is about a woman who went from winning an Oscar – the pinnacle of her career – to marrying a prince,” she added. Characterizing Grace and Rainier (played in the film by Tim Roth) as “an iconic couple,” Kidman added that being a princess requires “a set of protocols and rules.”

“She had to learn to be that, it doesn’t just happen. That requires skill, commitment and respect. She had to play a role – which was to be a princess,” she said.

The Monaco royals initially offered to cooperate with the film’s production, but withdrew their support from the project. Once shooting was finished, disagreement between the director and the film’s U.S. distributor over editing led to postponement and a possible drop from wide U.S. release.

These problems have now been resolved, the paper suggests.

Check back with PEOPLE.com starting May 14 for photos, video and inside scoop on all the glamorous goings-on at the Cannes Film Festival!